From time to time, pneumatic tires require repair or replacement. To service such tires, the tire must be removed from the wheel rim. A variety of tools have been developed and utilized to facilitate the working of tire. Such tools typically comprise an elongate bar having a handle and a working end adapted to be inserted between the tire bead and wheel rim. The working end of the tool frequently has a flattened or tapered portion to facilitate insertion of the working end between the tire bead and the wheel rim. The working ends of known tools are configured, in profile, as either straight, curved, or angled.
To utilize the implement, the tool working portion is inserted manually between the bead of the tire and its associate wheel rim. Thereafter, the user applies pressure on the handle and moves a portion of the working end into contact with the wheel rim, whereby establishing the wheel rim as a fulcrum and making a lever of the tool. Pressure upon the handle causes the tool working end to engage and move a segment of the tire bead inward and allows the tire bead to be stretched over the rim by moving the tool around the periphery of the tire. In more recent years, machines have been developed which rotate the tire in conjunction with the use of the tool to alleviate the need for moving the tool.
While the prior art is replete with working tools, the basic design has not changed significantly over the years. Known designs, while working well to an extent, have proven less than satisfactory in providing an optimally functional tire working implement. Some known devices remove tubeless truck tires by using separate tools for each tire bead. A first working tool is used to stretch the first bead of the tire over the rim. Then, a second working tool is inserted between the second tire bead and the wheel rim and leverages the second bead over the rim to complete removal of the tire. Use of separate implements, however, increases cost and complicates the procedure.
To aid in the removal process, some designs incorporate a projection that extends from the bottom of the flattened portion to create additional leverage when engaged with the wheel rim. Projections, however, carry a disadvantage in that they contact the wheel rim at a single point. Other devices use rollers as the pivot point between the tool and wheel rim. Rollers are undesirable in use because they are prone to movement during the working process and such movement can reduce the mechanical advantage provided by the tool. Still other designs use a bend in the mounting tool working end to create a pivot point. A bend is advantageous to an extent but, as with a projection, it provides only a single point of contact with the wheel rim. With only one point of contact, the tool is prone to rocking or slipping on the rim during the tire removal procedure. Rocking or slipping can dislodge the working tool and require the user to begin the working process anew. At best, rocking or slipping necessarily causes the user to exert additional effort and concentration to maintain the working tool in its proper position.
An additional disadvantage attends the use of conventional working tools. During the working process, the first tire bead is typically removed first by laying the tire flat on the ground or other supporting surface and inserting the working tool between the first bead and the rim. The tool is then used as a lever to work the first bead over the rim. After the first bead is removed from its position on the rim, the tire is then lifted to enable insertion of the second bead working tool between the second bead and the rim. Thereafter, the tire is dropped and acts under force of gravity to free the second bead. As can be appreciated, this repeated manual elevation of tires requires a significant amount of exertion by the user and may be impractical for less powerful users of the tool.
Other known second working tool designs comprise a straight tool having a tip that angles downwardly from the longitudinal plane of the tool. While a downward bend creates a more efficient lever, the downwardly turned tip, however, makes insertion difficult and requires inserting the tip at a sideways angle to the bead. A user will typically insert the tip between the tire bead and the wheel rim, leading with a corner of the tip, and gradually working the remainder of the tip underneath. This process is time consuming, and requires significant effort. A further disadvantage is that, once inserted, the straight portion of the tool presses against the sidewall and tread of the tire in the course of leveraging the tire bead. Since only the bead must be raised outside of the rim, the force exerted against the sidewall and tread does not directly contribute toward a removal of the bead. The flexible sidewall, in fact, absorbs a significant amount of force through deformation before useful force is transmitted to the bead. Thus, more force is required to operate such tools and represents, again, an ergonomic disadvantage to the user. Moreover, by impinging against and applying a significant leveraging force against the sidewall of the tire, conventional tools can cause damage to the tire sidewall and tread areas.
As a consequence, there is a need for a working tool that reduces the likelihood of rocking or sliding of the tool during tire removal. There is a further need for a working tool that is more easily inserted between the bead and the rim. There is a further need for a working tool that does not rest against the sidewall while leveraging the second tire bead from the wheel rim. There is a further need for a working tool that does not require that the tire be lifted by the user in order to remove the second tire bead from the wheel rim.